Bupleurum, Genus, rotundifolium, Species,
- Genus & species
Thorow-wax
Europe, North Africa, and western Asia
SunFull Sun
Overview
Bupleurum rotundifolium is an upright annual in the carrot family, growing 12-30 inches (30-75 cm) tall with branched, wiry stems. The blue-green leaves are oval to rounded and perfoliate, with the stem appearing to pass through the center of each leaf, 1-2.5 inches (2.5-6 cm) long. From early summer into autumn, flat umbels of small yellow-green flowers open above broad, leaf-like green bracts that ring each cluster; the umbels are 1-2 inches (2.5-5 cm) across. The flowers give way to small ribbed seeds. The whole plant has a blue-green cast and a stiff, branching form. It self-seeds in open ground and was once a weed of cereal fields across Europe. Plants complete their cycle in a single season and die after setting seed.
Native Range
Native to Europe, North Africa, and western Asia, and naturalized more widely. Grows on disturbed ground, field margins, and calcareous soils in full sun. Once common in cereal crops, it has declined across much of its arable range.Suggested Uses
Grown in cutting gardens and mixed borders at 8-10 inch (20-25 cm) spacing, where the umbels and green bracts are used as filler in fresh arrangements. Self-seeds into gravel and open ground. Soft stems in rich soil need support or closer spacing.How to Identify
Appearance
Size & Dimensions
Height1' - 2'6"
Width/Spread8" - 1'
Colors
Foliage Colors
Bloom Information
Detailed Descriptions
Foliage Description
Blue-greenGrowing Conditions
Sun Requirements
Requires 6-12 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Water & Climate
Water Needs
Drought Tolerance
Drought tolerant when established
Care & Maintenance
Care Guide
Grows in full sun in well-drained soil and tolerates poor, dry, and chalky ground. Performs poorly in rich, moist soils, where stems grow soft and flop. Water sparingly, as the plant tolerates dry conditions once established. Self-seeds in open ground, returning from year to year where seedlings are left. Aphids occur on soft growth. Plants die after setting seed in autumn.Pruning
Remove spent stems to limit self-seeding, or leave them to drop seed for the following year. Cut stems for use as cut foliage as the umbels open. No other pruning is needed.Pruning Schedule
Prune: October
fall
Container Growing
Suitable for container growing
Minimum container size: 2 gallons
Toxicity: Not assessed
UnknownPlanting Guide
Planting Methods & Timing
Planting Method
direct sow
Direct Sow Timing
Sow in spring where plants are to grow, or in autumn in mild areas; seeds germinate in cool to warm soil.
Days to Maturity
90–120 days
Plant Spacing
9 inches
